This invention relates to glass production and, more particularly, to an apparatus for use with an electric furnace for supporting an electrode and insulating such electrode from the electrode jack associated therewith. It is intended that the term "electric furnace," as used herein, denotes both electric melt and electric boost furnaces.
In electric furnaces for melting electrically semiconductive material, such as glass, it is important that the insulation around the electrodes be maintained in excellent condition. If the insulation fails, operating personnel may be subjected to a serious shock hazard. Moreover, such insulation failure may result in significant damage to equipment, thus resulting in a shutdown of the furnace. Poor insulation may be caused by either (a) breakdown of the existing insulation material due to cracks or chemical change caused by the local environment or (b) creepage on the insulating material, i.e., the flowing of electricity along the surface of the insulator. The creepage problem is intensified when dust and/or moisture collect on the insulator.
The electrode jack which is employed to support and align the electrode and to insert an additional portion of the electrode into the furnace as needed, is at ground potential. The electrode is attached to the electrode jack by an assembly which both supports the electrode and insulates it from the electrode jack. It has been found that the insulation of the prior art jack head assemblies fails when subjected to the harsh environment of a glass production furnace. Moreover, the prior art jack head assemblies cannot be easily cleaned and visually inspected, thereby intensifying the problem. In addition, if insulation breakdown was detected before an actual short circuit, the jack stand and the jack head assembly have to be lowered in order to replace the deteriorated insulation.
Therefore, it is an object of this invention to provide a reliable and safe jack head assembly that resists creepage and is easily cleaned, inspected and replaced.